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Personal genomics firms must come clean

Companies that offer analyses of future health risks based on basic genetic tests should be more transparent about the limitations of their predictions, says genomics pioneer Craig Venter.

He and four colleagues have proposed guidelines for the industry after assessing the results of scans of their own personal genomes as provided by the Californian firms 23andMe and Navigenics. They found the companies recorded the genetic markers consistently at least 99.7 per cent of the time, but diverged on their assessment of the associated health risks.

That’s similar to New Scientist‘s comparison earlier this year of the results of scans from 23andMe and a third company, Decode Genetics of Reykjavik, Iceland. In this case the genetic markers were consistently recorded 99.996 per cent of the time.

Beg to differ

For four common diseases, the companies agreed for Venter and his colleagues on whether each had a reduced, average, or increased risk. But for seven other conditions, they came up with different answers for at least two of the group.

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The predictions were particularly varied for the skin disease psoriasis&colon; in Venter’s case, 23andMe put his risk at more than four times a typical person’s, whereas Navigenics said it was just 25 per cent above average.

New Scientist also obtained divergent predictions for psoriasis – 23andMe put our reporter’s relative risk at 13 per cent below average, while Decode suggested that he faced a mere third of the typical risk. Such differences arise largely because the companies look at different collections of genetic markers.

Venter, who heads his own institute in San Diego, California, and colleagues, recommend that companies should agree on a core set of markers with strong effects for each disease.

They also suggest that both companies and customers should focus attention on the diseases with the highest risk predictions – which are likely to remain significant even as more information accumulates.

Whole genomes

The group argues that companies should be more transparent about the limitations of their predictions by telling customers what proportion of their genetic risk can be accounted for by the markers in the scans.

For instance, 23andMe currently tells customers that about 26 per cent of the risk of developing type 2 diabetes is due to genetic factors, but it does not stress that the nine markers it scans for the condition only account for only a fraction of this figure. “We do have estimates, and we will consider how best to communicate them to our customers,” says Andro Hsu of 23andMe.

Geneticists still know remarkably little about how differences in people’s DNA affect health, says Venter. “My whole genome is out there and it can’t give me much more information than the personal genomics companies.”

Once several thousand people have had their genomes fully sequenced, says Venter, what’s needed is the collection of detailed health data from all of these individuals.